On 2023/8/17 22:50, Bart Van Assche wrote:
> On 8/17/23 07:41, kernel test robot wrote:
>> [ 222.622837][ T2216] statistics for priority 1: i 276 m 0 d 276 c 278
>> [ 222.629307][ T2216] WARNING: CPU: 0 PID: 2216 at block/mq-deadline.c:680 dd_exit_sched (block/mq-deadline.c:680 (discriminator 3))
>
> The above information shows that dd_inserted_request() has been called
> 276 times and also that dd_finish_request() has been called 278 times.
Thanks much for your help.
This patch indeed introduced a regression, postflush requests will be completed
twice, so here dd_finish_request() is more than dd_inserted_request().
diff --git a/block/blk-mq.c b/block/blk-mq.c
index a8c63bef8ff1..7cd47ffc04ce 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -686,8 +686,10 @@ static void blk_mq_finish_request(struct request *rq)
{
struct request_queue *q = rq->q;
- if (rq->rq_flags & RQF_USE_SCHED)
+ if (rq->rq_flags & RQF_USE_SCHED) {
q->elevator->type->ops.finish_request(rq);
+ rq->rq_flags &= ~RQF_USE_SCHED;
+ }
}
Clear RQF_USE_SCHED flag here should fix this problem, which should be ok
since finish_request() is the last callback, this flag isn't needed anymore.
Jens, should I send this diff as another patch or resend updated v3?
Thanks.
> Calling dd_finish_request() more than once per request breaks the code
> for priority handling since that code checks how many requests are
> pending per priority level by subtracting the number of completion calls
> from the number of insertion calls (see also dd_queued()). I think the
> above output indicates that this patch introduced a regression.
>
> Bart.
>
